JPH0770538A - Reactive hot-melt adhesive composition - Google Patents

Abstract

PURPOSE:To obtain a reactive hot-melt adhesive composition having assured high spreadability and exhibiting excellent adhesive properties in the initial and final stage of bonding. CONSTITUTION:This composition comprises a reaction product of a low- molecular-weight hydroxyl-terminated polyester having a number-average molecular weight of 1000-6000 with 1.5-4.0 equivalents, per equivalent of the hydroxyl groups of the low-molecular-weight polyester, of a polyisocyanate compound, and the low-molecular-weight polyester comprises 10-90wt.% lowly crystalline polyester having a heat capacity of crystal fusion of below 5.0cal/g as measured by DSC and 90-10wt.% highly crystalline polyester having a heat capacity of crystal fusion of 5.0cal/g or above as measured by DSC.

Description

Detailed Description of the Invention

[0001]

The present invention is excellent in workability of coating,
The present invention relates to a reactive hot melt adhesive composition having excellent initial bond strength and final bond strength.

[0002]

2. Description of the Related Art As a reactive hot melt adhesive composition, a reactive hot melt adhesive composition comprising a reaction product of a polyester having a hydroxyl group at a terminal and a polyvalent isocyanate compound is disclosed in JP-A-2-140284. It is conventionally known as described in the above.

As the polyester in the reactive hot melt adhesive composition, a high molecular weight polyester is used for the purpose of improving initial physical properties such as initial adhesive strength.

[0004]

However, a reactive hot melt adhesive composition using a high molecular weight polyester has a relatively high melt viscosity, and therefore, when the adhesive composition is applied to an adherend. In addition, not only a high temperature and a high discharge pressure are required, but also it is difficult to make the adhesive layer thin, and the workability of coating is not good.

On the other hand, a reactive hot melt adhesive which uses a low molecular weight polyester having a low melt viscosity and good workability for coating as a polyol component has been conventionally used as described in the prior art section of the above-mentioned publication. It is known that satisfactory initial physical properties of adhesion cannot be obtained.

In view of the above situation, the present invention is a reactive hot melt adhesive having a high initial bond strength and a high final bond strength even though a low molecular weight polyester having good coating workability is used as a polyol component. It is intended to provide a composition.

[0007]

The reactive hot melt adhesive composition of the present invention achieves this object, and comprises a low molecular weight polyester having a hydroxyl group at the terminal and a number average molecular weight of 1000 to 6000, and In a reactive hot melt adhesive composition comprising a reaction product of a polyvalent isocyanate compound in an amount of 1.5 to 4.0 equivalent times the hydroxyl value of the low molecular weight polyester, the low molecular weight polyester is (a) DS.
From 10 to 90% by weight of a low crystalline polyester having a heat of fusion of less than 5.0 cal / g measured by C and (b) 90 to 10% by weight of a highly crystalline polyester having a heat of fusion of 5.0 cal / g or more measured by DSC. It is characterized by becoming.

Further, the low molecular weight polyester can obtain good coating workability by having a melting point of 120 ° C. or less and a melt viscosity at 120 ° C. of 50 poise or less.

The low crystalline polyester which constitutes the reactive hot melt adhesive composition of the present invention is an aromatic polycarboxylic acid such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, trimellitic acid or pyromellitic acid, and amber. Acids, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, aliphatic polycarboxylic acids such as eicosanedioic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4- One or more selected from cycloaliphatic polycarboxylic acids such as cyclohexanedicarboxylic acid, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-
Pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, neopentyl glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, polytetramethylene glycol, 1,4- An esterification reaction is carried out with one or more selected from polyhydric alcohols such as cyclohexanedimethanol, hydrogenated bisphenol A, trimethylolethane, trimethylolpropane, and pentaerythritol, and if necessary, polycondensation is carried out so as to have a hydroxyl group at the terminal. To prepare. Incidentally, lactones such as ε-caprolactone, and oxyacids such as p-oxybenzoic acid and p-oxyethoxybenzoic acid may be used in combination with the above polycarboxylic acids and polyhydric alcohols.

The low crystalline polyester is not limited to the copolyester as long as it has a hydroxyl group at the terminal and has a heat of fusion measured by DSC of less than 5 cal / g, but it is low crystalline and relatively Since a low melting point is desirable, it may be a copolyester using at least one of a polyvalent carboxylic acid and a polyhydric alcohol, or a polyester in which an oxyacid is used in combination with a polycarboxylic acid and a polyhydric alcohol. desirable.

On the other hand, the highly crystalline polyester constituting the reactive hot melt adhesive composition of the present invention is a highly crystalline polyester having a hydroxyl group at the terminal and having a heat of fusion measured by DSC of 5.0 cal / g or more. Although it may be present, it is usually desirable to prepare it by using one type of each of the polyvalent carboxylic acid and the polyhydric alcohol, and it is particularly desirable that the polyvalent carboxylic acid has an even number of carbons.

The above-mentioned highly crystalline polyester may be a copolyester, but even when two or more kinds of either a polyvalent carboxylic acid or a polyhydric alcohol are used, 20 mol% or less of one component of the two or more kinds, 80 of two or more other ingredients
It is desirable that the polyvalent carboxylic acid and the polyhydric alcohol are selected such that the heat capacity for fusion is 5 cal / g or more, preferably 10 cal / g or more, by using them in a ratio of not less than mol% and copolymerizing.

The low crystalline polyester and the high crystalline polyester have a molecular weight of 1000 to 6000, preferably 1500 to 6000.
It's 4000.

When the molecular weight is less than 1000, the initial adhesive strength is insufficient, while when the molecular weight is 6000 or more, the melt viscosity is high and the workability of coating on the adherend becomes poor.

The polyvalent isocyanate compound constituting the reactive hot melt adhesive composition of the present invention includes tolylene diisocyanate, m-phenylene diisocyanate,
p-phenylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, decamethylene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, 4,4′-methylene bis (cyclohexane diisocyanate), 4,4'-diphenylmethane diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, isophorone diisocyanate, 1,5-
Examples thereof include naphthalene diisocyanate and 2,6-naphthalene diisocyanate, and one or more of these are used.

The amount of the polyvalent isocyanate compound is 1.5 to 4.0 equivalent times, preferably 2.
Use 0 to 3.5 equivalent times.

That is, if the amount of the polyvalent isocyanate compound is less than 1.5 equivalent times the hydroxyl value of the polyester, the melt viscosity when blended in the polyester is significantly increased, and the workability of coating on the adherend becomes poor, On the other hand, when it exceeds 4.0 equivalent times, the initial bonding strength becomes low.

The low crystalline polyester, the highly crystalline polyester and the polyvalent isocyanate compound are 150 ° C. or less,
It is preferable to mix and react at a temperature of about 120 ° C. to prepare a reactive hot melt adhesive composition having an isocyanate group at the molecular end.

The above isocyanate group reacts in the presence of water and contributes to curing.

The reactive hot melt adhesive composition of the present invention comprises a rosin, a rosin ester, a hydrogenated rosin ester, a terpene, a terpene phenol, and a hydrogenated compound, in addition to the low crystalline polyester, the highly crystalline polyester and the polyvalent isocyanate compound. Natural resins such as terpenes, C ₅ aliphatic resins, petroleum resins such as C ₉ aromatic resins, calcium carbonate,
A crystallization accelerator such as talc can be used if necessary.

Production Example 1 of Low Crystalline Polyester 582 parts by weight of dimethyl terephthalate, 1,4-butanediol
324 parts by weight was taken in a reaction can, 0.5 parts by weight of tetra-n-butyl titanate was added as a catalyst, and transesterification reaction was carried out at 160 ° C to 240 ° C under normal pressure to distill off almost the theoretical amount of methanol. . Then 1022 parts by weight of adipic acid,
Add 666 parts by weight of 1,4-butanediol, 180 ℃ ~ 240 ℃
An esterification reaction was carried out to distill off and remove almost the theoretical amount of water to prepare a polyester having an acid value of 1.8, a hydroxyl value of 48.3, and a number average molecular weight of 2240 calculated from the acid value and the hydroxyl value (referred to as polyester A). ). Of the polyester A
The melt viscosity at 120 ° C. was 12.0 poise, the melting point measured by DSC was 70 ° C., and the heat capacity of fusion was 2.5 cal / g.

Production Example 2 of Low-Crystalline Polyester As in Production Example 1 above, except that 1,4-butanediol added in the esterification reaction together with adipic acid was increased to 846 parts by weight to obtain an acid value of 1.5 and a hydroxyl value. A low crystalline polyester oligomer having a molecular weight of 137.7 and a number average molecular weight of 810 was prepared (referred to as polyester B). 12 of the above polyester B
The melt viscosity at 0 ° C. was 3.1 poise, the melting point measured by DSC was 48 ° C., and the heat capacity of fusion was 1.2 cal / g.

Production Example 3 of Low-Crystalline Polyester A polyester oligomer prepared in the same manner as in Production Example 2 above was subjected to a polycondensation reaction at 200 to 240 ° C. under reduced pressure to give an acid value of 1.6.
A high molecular weight polyester having a hydroxyl value of 4.0 was prepared. Subsequently, 18 parts by weight of 1,4-butanediol was added, and a depolymerization reaction was carried out at 240 ° C. under a pressure of 0.5 kg / cm ² with nitrogen to obtain a low crystal having an acid value of 2.0, a hydroxyl value of 13.5 and a number average molecular weight of 7240. A reactive polyester was prepared (referred to as polyester C). The above polyester C has a melt viscosity at 120 ° C. of 57.3 poise, a melting point measured by DSC of 74 ° C., and a melting heat capacity of 2.9 cal.
It was / g.

Production Example of Highly Crystalline Polyester Using 773 parts by weight of dodecanedioic acid and 348 parts by weight of 1,4-butanediol, an esterification reaction was carried out under atmospheric pressure at 180 to 240 ° C. to obtain an acid value of 1.7 and a hydroxyl value of 54.8. A highly crystalline polyester having a number average molecular weight of 1990 was prepared (referred to as polyester D). The melt viscosity of the above polyester D at 120 ° C. was 10.1 poise, the melting point measured by DSC was 75 ° C., and the melting heat capacity was 27.3 cal / g.

The characteristics of each of the above polyesters were measured by the following methods. Acid value: The sample was dissolved in 1,4-dioxane and directly determined by titration with a methanolic potassium hydroxide solution. Hydroxyl value: The sample was dissolved in pyridine, excess acetic anhydride was added to esterify the hydroxyl group, and excess acetic anhydride and acetic acid were back-titrated with a methanolic potassium hydroxide solution. Melting point and heat capacity of fusion: Perkin-Elmer DSC
Using -7 type, heat up to 150 ℃ at a rate of 20 ℃ / min,
Hold at 150 ° C for 3 minutes, cool at 20 ° C / min to 20 ° C, and
The temperature was measured again after the temperature was raised again at ° C / min. Melt viscosity: Using Brookfield B viscometer
After holding at 120 ° C for 1 minute, the measurement was performed.

[0026]

【Example】

Examples 1 to 4 and Comparative Examples 1 to 4 Polyesters and 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as MDI) prepared in the above Production Example were taken in the amounts shown in Table 1, and the amount was 2 at 120 ° C under a nitrogen gas atmosphere. After stirring and mixing for a period of time, a reactive hot melt adhesive composition having 2.5 equivalents of isocyanate groups with respect to hydroxyl groups and having melt viscosity shown in Table 1 was prepared. Subsequently, each of the above adhesive compositions was applied to a No. 9 canvas at 120 ° C using a roll coater, and the canvas and the adhesive were not applied.
After pasting with No. 9 canvas and hand roller,
The peel strength and the temperature rising softening point were measured and the results shown in Table 1 were obtained.

The peel strength and the temperature rising softening point in Table 1 were measured by the following methods. Peel strength: Measured by peeling a canvas having a bonded portion of 2.5 cm × 2.5 cm with RTA-100 type Tensilon manufactured by Orion Tech at a tensile speed of 20 cm / min. In addition, this measurement was performed for each sample 2 minutes, 24 hours, and 72 hours after laminating. Temperature rising softening point: Fix one of the two canvases with a 2.5cm x 2.5cm laminating area in the dryer, and set 30 on the other canvas.
A weight of 0 g was hung and hung, the temperature inside the dryer was raised at a rate of 2 ° C / 5 minutes, and the dropping temperature was measured. The measurement was performed 72 hours after the bonding.

[0028]

[Table 1]

Examples 5-7 and Comparative Examples 5, 6 As in Example 2, except that the amount of MDI was taken as in Table 2 to prepare a reactive hot melt adhesive composition and Example 2
The evaluation was performed in the same manner as above, and the results shown in Table 2 were obtained.

[0030]

[Table 2]

The adhesive composition of Comparative Example 5 showed a remarkable increase in viscosity and could not be used for evaluation of melt viscosity and adhesive performance.

As is clear from the data of Examples 1 to 4, the low crystalline polyester and the high crystalline polyester were
It has been found that by using the mixture in a preferable ratio of 10 to 90% by weight and 90 to 10% by weight, the peeling strength at the initial stage of adhesion and after 72 hours is high and the adhesive having heat resistance is possible. .

On the other hand, as shown in Comparative Example 1, when the ratio of the highly crystalline polyester exceeded 90% by weight, the coagulation was too fast and the adhesive strength was low. In addition, as shown in Comparative Example 2, when the ratio of the low crystalline polyester exceeds 90% by weight, it takes a long time to solidify, and the peel strength at the initial stage of adhesion becomes low.

Further, as shown in Comparative Example 3, when the molecular weight of the polyester is too low, the peel strength at the initial stage of adhesion becomes extremely low. On the other hand, as shown in Comparative Example 4, when the molecular weight of the polyester is too high, The final peel strength was low and the temperature rising softening point was also low.

Further, as shown in Examples 5 to 7 and Comparative Examples 5 and 6, it is preferable to select the equivalent ratio (NCO / OH) of the isocyanate group and the hydroxyl group of the polyester in the range of 1.5 to 4.0. It can be seen that it is essential for maintaining the performance of the melt adhesive composition.

[0036]

As is apparent from the above description, according to the present invention, in preparing the reactive hot melt adhesive composition, the low crystalline polyester and the high crystalline polyester are added in an amount of 10 to 90% by weight. With a ratio of 90 to 10% by weight, a relatively low molecular weight and therefore a low melt viscosity,
It is possible to provide a reactive hot melt adhesive composition having excellent adhesive performance both in the initial stage and in the final stage, while ensuring high coating workability.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naomi Sasaki 23 Uji Kozakura, Uji City, Kyoto Prefecture Unitika Ltd. Central Research Laboratory (72) Inventor Kikumi Nakamichi 23 Uji Kozakura, Uji City Kyoto Prefecture Unitika Co. Ltd. Central (72) Inventor Shingo Sasaki 4085 Nakatsu, Aikawa-cho, Aiko-gun, Kanagawa Diabon Kogyo Co., Ltd.Atsugi Plant (72) Inventor Tomohisa Uemura 4085, Nakatsu, Aikawa-cho, Aiko-gun Kanagawa Prefecture Atsugi Plant, Atsugi Plant

Claims (1)

[Claims] 1. A number average molecular weight of 1000 having a hydroxyl group at the terminal.
In a reactive hot melt adhesive composition comprising a reaction product of a low molecular weight polyester of 6000 to 6000 and a polyisocyanate compound of 1.5 to 4.0 equivalent times the hydroxyl value of the low molecular weight polyester, the low molecular weight polyester is ( a) 10 to 90% by weight of a low crystalline polyester having a heat of fusion measured by DSC of less than 5.0 cal / g, and (b) a highly crystalline polyester having a heat of fusion measured by DSC of 5.0 cal / g or more.
A reactive hot melt adhesive composition comprising 90 to 10% by weight.